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A Theoretical Probe of Mechanistic Trichotomy in Rh III ‐Catalyzed Annulation with Alkyne MIDA Boronates: Roles of Salt, Solvent, and Coupling Partner
Author(s) -
Zhao Liu,
Fang DeCai
Publication year - 2015
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201500329
Subject(s) - chemistry , annulation , alkyne , catalysis , chemoselectivity , regioselectivity , intramolecular force , reactivity (psychology) , substituent , medicinal chemistry , yield (engineering) , solvent effects , solvent , stereochemistry , photochemistry , organic chemistry , medicine , materials science , alternative medicine , pathology , metallurgy
Abstract A theoretical study of the role of added salts, solvent effects, and substrate scope for the Rh III ‐catalyzed C–H activation and annulation of N ‐(pivaloyloxy)benzamide and alkyne MIDA boronates has been performed by means of DFT calculations. Computationally, the high reactivity of terminal alkynyl MIDA boronates originates from the electronic stability of the sp 3 ‐hybridized boronate. The critical role of Cu(OAc) 2 as additive is such that it can be viewed as an intermediate catalyst, assisting the removal of the directing group and facilitating the conversion of Rh I into Rh III in the intramolecular oxidative addition process. In contrast, AgOAc seems to have an opposite effect because it increases the activation free‐energy barrier for the migratory insertion step, retarding the chemical transformation and reducing the product yield. Solvent selectivity, regioselectivity and substituent effects have also been investigated.